Curtiss HS

{{short description|American single engine patrol flying boat (1917–1928)}}  {{Infobox aircraft |name=HS |image=Curtiss HS-2 NAN10-48.jpg |caption=A Curtiss HS-2L |type=Patrol flying boat |manufacturer=[[Curtiss Aeroplane Company|Curtiss]] |designer= |first_flight=[[1917 in aviation|1917]] |introduction=1918 |retired=1928 (USN) <br> 1926 (USCG) |status=Retired |primary_user=United States Navy |more_users=Canada, Portugal |produced=1917-1919 |number_built=ca. 1,178 |variants= }}

The '''Curtiss HS''' was a single-engined patrol [[flying boat]] built for the [[United States Navy]] during [[World War I]]. Large numbers were built from 1917 to 1919, with the type being used to carry out anti-submarine patrols from bases in France from June 1918. It remained in use with the US Navy until 1928, and was also widely used as a civil passenger and utility aircraft.

==Development and design==

In late 1916, the [[Curtiss Aeroplane Company]] produced a new twin-engined [[flying boat]], which was smaller than both the current [[Curtiss Model H|Curtiss H-12]] being built for Britain's [[Royal Naval Air Service]] and the earlier Curtiss H-4, with the new design given the factory designation '''Model H-14''', although its design was unrelated to earlier Model H variants. The H-14 was a conventional unequal-span, unstaggered biplane, powered by two 100 hp (75 kW) [[Pusher configuration|pusher]] [[Curtiss OXX]] engines mounted between the wings. An order for 16 was placed by the [[United States Army]] before the prototype flew, but the prototype was disappointing and the US Army cancelled its order for H-14s.<ref name="Bowers curtiss p93-4">Bowers 1979, pp. 93–94.</ref>

[[File:Curtiss HS assembly c1918.jpeg|thumb|HS-1 production at Curtiss, in 1917-1918.]]

The prototype was converted to a single-engined aircraft powered by a 200 hp (149 kW) [[Curtiss V-X-X]] engine, also in a pusher configuration, during 1917, being redesignated as the '''Curtiss HS-1''' (for H model with single engine).<ref name="Bowers curtiss p93-4"/> The prototype was re-engined for use as a testbed for the new [[Liberty engine|Liberty 12]] engine, becoming the '''HS-1L''', flying in this form on 21 October 1917.<ref name="Swan navy p109">Swanborough and Bowers 1976, p.109.</ref>

While Curtiss's V-X-X engine proved to be inadequate, as it did in its larger Model H cousins, the Liberty proved more suitable, and large orders were placed by the US Navy for the HS-1L.<ref name="Swan navy p109"/> The {{nowrap|HS-1}} was armed with two 180 lb (80 kg) depth bombs, but it was found that these bombs were too small. In order to carry more powerful 230 lb (100 kg) bombs, Curtiss produced an increased-span version, the '''HS-2''' with span increased by 12 ft (3.66 m) and an additional set of [[interplane struts]], giving four-bay wings rather than the three-bay wings of the HS-1L.<ref name="Bowers curtiss p102-3">Bowers 1979, pp. 102–103.</ref> Again, Curtiss specified one of their own engines, and again, the Navy substituted this with the Liberty engine in the definitive '''HS-2L'''.{{Citation needed|reason=source needed for Curtiss engine HS-2 - Nothing in Bowers about it|date=March 2010}}

The '''HS-3''' was a further improved version with a new, wider, flat-sided hull, that eliminated the typical Curtiss sponsons. The end of the war brought an end to plans to mass-produce this version, only six being built.<ref name="Bowers Curtiss p104"/><ref name="Owers p67"/>

The HS-1L and -2L were built in vast quantities: 675 by Curtiss themselves, and nearly as many again by various contractors that included [[Lowe, Willard & Fowler Engineering Company|L-W-F]] (250), [[Standard Aircraft Corporation|Standard]] (80), [[Gallaudet Aircraft Company]] (60), [[Boeing]] (25) and [[Loughead Aircraft Manufacturing Company|Loughead]] (2). A further 25 were assembled by the US Navy from spare parts postwar.<ref name="Bowers curtiss p103">Bowers 1979, p.103.</ref>

==Operational history== The HS-1L began to enter service early in 1918, flying anti-submarine patrols from a number of [[Naval Air Station]]s on the Eastern Seaboard of the United States, and from the [[Panama Canal Zone]]. Two HS-1Ls operating from [[Chatham, Massachusetts]], made the only confirmed aircraft attack on a German {{nowrap|[[U-boat]]}} in American waters on July 21, 1918, but this was unsuccessful, with bombs failing to explode and the submarine escaping.<ref name="Owers p68">Owers 1999, p.68.</ref> From August 1918, in order to compensate for Canada's lack of patrol aircraft, US Navy HSs operated from two bases in [[Nova Scotia]]. Twelve HS-2Ls were donated to Canada at the end of the war.<ref name="Owers p68"/><ref name="canwings">{{cite web|url=http://www.canadianwings.com/Aircraft/aircraftDetail.php?HS-2L-151|archive-url=https://web.archive.org/web/20110708113430/http://www.canadianwings.com/Aircraft/aircraftDetail.php?HS-2L-151|url-status=usurped|archive-date=July 8, 2011|title=Royal Canadian Air Force, Curtiss HS-2L|work=canadianwings.com|access-date=15 March 2010}}</ref>

[[File:Curtiss HS-2L over Pensacola 1920s.jpeg|thumb|An HS-2L over [[Pensacola, Florida]] in the 1920s.]]

Large numbers of HS boats were also used by US Navy forces in France, with deliveries starting on May 24, 1918, flying their first patrols on June 13. About 160 HS-1Ls and -2Ls were deployed to France.<ref name="Owers p70">Owers 1999, p.70.</ref><ref name="Bowers Curtiss p102">Bowers 1979, p.102.</ref> Following the [[Armistice with Germany (Compiègne)|Armistice]], the HS boats based in Europe were scrapped apart from four aircraft based in the Azores, which were acquired by Portugal, while the US Naval Air Service shrank considerably, with many Naval Air Stations closing, resulting in considerable numbers of HS boats becoming surplus to requirements and available for sale at $200 to $500 without engines.<ref name="Owers p71">Owers 1999, p.71.</ref> HS-2Ls continued in use by the US Navy as a patrol aircraft and a trainer until 1928.<ref name="Owers p74"/>

Following the Armistice, eleven HSs passed into US Coast Guard service, remaining in service until 1926.<ref name="Owers p75">Owers 1999, p.75.</ref><ref name="USCG">{{cite web |url=http://www.uscg.mil/History/webaircraft/CurtissHS2L.pdf |title=Curtiss HS-2L Flying-Boat |work=U.S. Coast Guard Aviation History |publisher=U.S. Coast Guard |access-date=15 March 2010}}</ref> As many as 83 HS boats were used by the [[United States Army Air Service]] for communications and survey purposes from overseas bases, although they were not given US Army serial numbers.<ref name="Owers p75"/>

Surplus HSs were also widely exported. Amongst Military users was Brazil, who received six aircraft in 1918.<ref name="curt lat p63"/> Two HS-2Ls were used in an attempt to bomb the rebel held Forte de [[Copacabana (Rio de Janeiro)|Copacabana]] during the 1922 [[Tenente revolts#July 1922: the first revolt|''Tenente'' revolt]].<ref name="Owers p74"/> Many were used in Canada as the first bush plane. One survives in the [[Canada Aviation Museum]] in [[Ottawa]] after being rescued from Foss Lake, Ontario.<ref name="Can mus">{{cite web |url=http://www.aviation.technomuses.ca/collections/artifacts/aircraft/CurtissHS-2L/ |title=Curtiss HS-2L La Vigilance |work=Canada Aircraft Museum |access-date=15 March 2010 |archive-url=https://web.archive.org/web/20100304073451/http://www.aviation.technomuses.ca/collections/artifacts/aircraft/CurtissHS-2L/ |archive-date=4 March 2010 |url-status=dead }}</ref>

==Variants== [[File:Curtiss HS-1 beached 1917.jpeg|thumb|An HS-1 in 1917.]] * '''HS-1''' - prototype with Curtiss engine.<ref name="Bowers Curtiss p101">Bowers 1979, p.101.</ref> ** '''HS-1L''' - early production version of HS-1 with Liberty engine and short span (62 ft 1 in (18.92 m)) wings.<ref name="Bowers Curtiss p105"/> * '''HS-2''' - longer-span version with Curtiss engine ** '''HS-2L''' - definitive production version with Liberty engine and long span (74 ft 1 in (22.58 m)) wings.<ref name="Bowers Curtiss p105"/> * '''HS-3''' - improved version of the HS-2L, with new, wider hull and larger fin. Only six aircraft were built.<ref name="Bowers Curtiss p104">Bowers 1979, p.104.</ref> * '''HS-3L''' - Canadian modified version of HS-2L with modified wings ([[Clark Y]] section). At least three converted.<ref name="Owers p67">Owers 1999, p.67.</ref>

==Operators== ;{{ARG}} *[[Argentine Naval Aviation]]<ref name="curt lat p63"/> Operated 12 aircraft from 1921 to 1931. ;{{flagcountry|BRA|1889}} *[[Brazilian Naval Aviation]] - acquired six HS-2Ls in July 1918.<ref name="curt lat p63"/> Retired in 1923.<ref>{{Cite web|url=https://www.aeroflight.co.uk/waf/americas/brazil/Navy/Brazil-naf_all-time.htm|title = Brazil Naval Aviation Aircraft Types}}</ref> ;{{flagcountry|CAN|1921}} *[[Canadian Air Board]] - acquired 12 HS-2L from the [[US Navy]] following closure of its [[Naval Air Station Halifax]]. Likely transferred to Canadian Air Force in 1923. *[[Canadian Air Force]] - obtained HS-2L beginning in 1920.<ref name="Bowers Curtiss p103-4">Bowers 1979, pp. 103–104.</ref> 12 likely transferred from Air Board when it disbanded and in total operated 30. All retired in 1928. ;{{flagcountry|MEX|1916}}<ref name="curt lat p63"/> *[[Mexican Air Force]] ;{{PER}} *[[Peruvian Navy]] - received at least three HS-2Ls in 1920, remaining in service until 1926.<ref name="curt lat p63">Hagedorn 1992, p. 63.</ref> ;{{Flagdeco|Philippines|1919|size=25px}} [[Insular Government of the Philippine Islands|Philippine Islands]] *Philippine Air Service - operated three HS-2Ls between 1920 and 1921. ;{{POR}} *[[Portuguese Naval Aviation]] - took over four ex-US Navy HS boats based in the [[Azores]] after the end of World War I, using them for training.<ref name="Owers p74">Owers 1999, p.74.</ref> Retired 1931. ;{{flagcountry|USA|1912}} *[[United States Army Air Service]] operated in total 83 HS-2L *[[United States Coast Guard]] operated 11 until 1926 *[[United States Marine Corps]] *[[United States Navy]]

==Specifications (HS-2L)== [[File:USCG HS-2L flying boat.jpg|thumb|Launching an HS-2L at U.S. Coast Guard Air Station Morehead City, North Carolina. Date unknown.]] {{Aircraft specs |ref=Curtiss Aircraft 1907–1947<ref name="Bowers Curtiss p105">Bowers 1979, p.105.</ref> |prime units?=imp  |crew=2 or 3 |length ft=39 |length in=0 |length note= |span ft=74 |span in=1 |span note= |height ft=14 |height in=7 |height note= |wing area sqft=803 |wing area note= |aspect ratio= |airfoil=RAF 6<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref> |empty weight lb=4300 |empty weight note= |gross weight lb=6432 |gross weight note= |max takeoff weight lb= |max takeoff weight note= |fuel capacity= |more general=  |eng1 number=1 |eng1 name=[[Liberty L-12]] |eng1 type=V-12 water-cooled piston engine |eng1 hp=360

|prop blade number=4 |prop name=fixed-pitch pusher propeller |prop dia ft= |prop dia in= |prop dia note=  |max speed mph=82.5 |max speed note= |cruise speed mph= |cruise speed note= |stall speed mph= |stall speed note= |never exceed speed mph= |never exceed speed note= |range miles=517 |range note=<ref name="Swan navy p111">Swanborough and Bowers 1976, p.111.</ref> |combat range miles= |combat range note= |ferry range miles= |ferry range note= |endurance=4 hours 30 minutes |ceiling ft=5200 |ceiling note= |g limits= |roll rate= |climb rate ftmin= |climb rate note= |time to altitude={{cvt|2300|ft}} in 10 minutes |wing loading lb/sqft= |wing loading note= |fuel consumption lb/mi= |power/mass= |more performance=

|guns= 1 × {{cvt|0.300|in|2}} [[Lewis gun]] in flexible mount |bombs= 2 × {{cvt|230|lb}} of bombs or depth charges carried under the wings }}

==See also== *[[Canadian Vickers]] - three HS-3L built

{{aircontent  |related= *[[Naval Aircraft Factory PT]] |similar aircraft= * [[Gallaudet D-4]] |sequence= |lists= |see also= }}

==Notes== {{Reflist}}

==Bibliography== * {{cite book|last= Bowers|first= Peter M.|author-link= Peter M. Bowers |title=Curtiss Aircraft 1907–1947 |year= 1979|publisher=Putnam |location=London |isbn=0-370-10029-8 }} * {{cite magazine |last1=Grant |first1=Robert S.|title= No Rope or Railing: Canada's Curtiss HS-2Ls|magazine=[[Air Enthusiast]] |issue=50 |pages=73–77|date=May–July 1993|issn=0143-5450 }} *{{cite magazine|last=Hagedorn|first=Dan|title=Curtiss Types in Latin America|magazine=[[Air Enthusiast]]|date=March–May 1992|issue=45 |pages=61–77 |issn=0143-5450}} * {{cite magazine |last1=Owers |first1=Colin A. |title= HS 'Boats: Curtiss HS Flying Boats|magazine=[[Air Enthusiast]] |issue=82 |pages=64–75|date=July–August 1999 |issn=0143-5450 }} * {{cite book |last1=Swanborough |first1=Gordon |last2=Bowers|first2=Peter M.|author-link2= Peter M. Bowers|title=United States Navy Aircraft since 1911|edition=Second |year= 1976|publisher=Putnam |location=London |isbn=0-370-10054-9 }} * {{cite book |last= Taylor |first= Michael J. H. |title=Jane's Encyclopedia of Aviation |year=1989 |publisher=Studio Editions |location=London |page=281 }} * {{cite book |title=Jane's All the World's Aircraft 1919 |publisher=Sampson Lowe Marston |location=London |pages=452a }}

==External links== {{Commons category|Curtiss HS}} * {{cite magazine |date=December 4, 1919 |title=The U.S. Navy HS-1L and HS-2L Flying-Boats |format=PDF |magazine=[[Flight (magazine)|Flight]] |volume=XI |issue=49 |id=No. 571 |pages=1550–1552 |url=http://www.flightglobal.com/pdfarchive/view/1919/1919%20-%201548.html |access-date=January 13, 2011 }} Contemporary technical description of the HS-1L and HS-2L with photographs and drawings. * [https://digitalcollections.museumofflight.org/nodes/view/2833 The HS-1L Flying Boat Handbook]

{{Curtiss aircraft}} {{Canadian Vickers aircraft}} {{LWF aircraft}} {{Aircraft manufactured in Canada}} {{Portal bar|Aviation}} {{Authority control}}

[[Category:1910s United States patrol aircraft]] [[Category:Flying boats]] [[Category:Curtiss aircraft|HS]] [[Category:Single-engined pusher aircraft]] [[Category:Biplanes]] [[Category:Aircraft first flown in 1917]]